Grade 11 Mathematics Practice Questions from Unit-7 In 2017/20

Flashcards for Grade 11 Mathematics Unit 7: Statistics

Which of the following is NOT continuous data?

Students' grade level 11

Average score of students who scored: 15 students scored 6, 20 students scored 7, 10 students scored 8 and 5 students scored 10.

7.2

The time needed to type a sample of 8 business letters in an office is 7, 8, 6, 8, 9, 7, 5, 6 minutes. What is the mean (x) and the standard deviation (sd) of the data in minute?

x=7, sd = √1.5

What is the sixth decile of the following frequency distribution table: Value: 4, 5, 6, 7, 8. Frequency: 3, 3, 5, 5, 5

7

Which one of the following is not true about measures of central tendency?

Mean is not affected by extreme values

What is the modal value of the distribution with the following data: Age 10-14, 15-19, 20-24, 25-29. Number of students: 2, 10, 6, 7

17.33

What is the mean and the variance of the following data respectively: X: 3-7, 8-12, 13-17, 18-22. Frequency: 4, 6, 8, 2

x=12, 8² = 25

There are three children in a room; ages three, four, and five, if a four-year-old child enters the room then which one of the following is true?

Mean age will stay the same but the standard deviation will decrease.

Marks obtained by 40 students in a short assessment are given below, where a and b are missing data. If the mean of the distribution is 7.2, what are the values of a and b respectively?

4, 3

The first group of 10 children has a mean weight of 15.6 kg, and the second group of another 10 children has a mean weight of 16 kg, and the third group of children has a mean weight 20 kg. If the mean weight of all children is 17 kg, what is the total number of children in all of the three groups?

29

Which of the following statements is not true about the data?

The range is 5

The following is a table showing the simple frequency distribution of a data set with variable x. What is the standard deviation of the data?

√3.6

A school has three class rooms for grade 11, namely, 11A, 11B, and 11C. The number of students in these classrooms is 28, 20, and 22, respectively. All the students took an examination, and the average scores of the students in 11A, 11B, and 11C are 60, 70, and 70, respectively. What is the average score for all grade 11 students?

65.67

The marks of students scored in an examination are grouped into class intervals as shown below. What is the median of the marks?

77.5

If the list of a measurement is 10, a, 5, a, 10, 20, 15,20,5, with mean x, then what is the value of a in terms of x?

5x-90

The following is the frequency distribution of a grouped data. What are the mean and the standard deviation of the distribution, respectively?

12.5, √15

The following is a set of data representing the average marks of 13 students. Then which of the following statements is true about the data?

The upper quartile is 92

A measurement is grouped into five class intervals with the following frequency distribution. What are the first quartile Q2 and the 75th percentile P75 of the measurement?

22

The following is a simple frequency distribution of a data with variable x. What are the mean x and variance 82 of the data?

x=5, 82 = 1.4

The marks of 50 students are given below. If the median of the data is 26, what are the values of fland f2?

fl=12,2=15

In a survey of 25 students about studying time in minutes notes that 25 students spent studying for a math test. If the mode of the data is 16.67, what are the values of Fland F2?

FI=6, F2=3

If the mean of a, b, c'd is k, then what is the mean of a+b,2b,c+b,b+d?

k+b

In an examination, the mean mark scored by a class of 40 students was calculated as 72.5. Later, it was detected that the marks of one student were wrongly copied as 48 instead of 84. What is the correct mean?

73.4

The mean monthly salary of 12 employees of a firm is Birr 1450. If one more person joins the firm who gets Birr 1645 per month, what will be the mean monthly salary of 13 employees?

1465

The daily rainfall for the last five days was 60, 90, 150, 210, 240. For the next five days, the amount of rainfall was doubled each day, i.e., 120, 180, 300, 420, and 480. What is the mean, variance, and standard deviation of the doubled rainfall respectively?

300, 2080, √2080

The following represents marks obtained in a mathematics exam (out of 60). What is the minimum pass mark if 70% of the student to pass:

36.58

In a small business 2 cleaners earn Birr 340 each, 6 persons handling the machinery earn Birr 600 each, the manager earns Birr 1500 and the director Birr 3500 per month. Which measure best represents these data?

Median

If the population function has mean (x) = 4 and mean (x2) = 24, then what is its standard deviation?

2√2

The Inter Quartile Range (IQR) is equal to

5

The mode is equal to

148.83

Let each value of a population function is increased by a constant number C. which of the following is NOT true?

The variance is increased by C

If the standard deviation of X1, X2, X3, …, X, is √5, then the standard deviation of 2x₁ +5, 2x2 +5, 2x3+5,…+ 2xn+ 5 is

2√5

What is the modal income in birr is

91.5

Among ten students who took a test, the list of the marks of eight of the students is: 10, 9, 11, 10, 16, 16, 18, 10. The list misses the marks of two students who scored equal marks. If the median of the marks of all the ten students is 13, then the two missed marks are equal to

14